Electrode for arc-lamps.



No. 889,937. PATENTED JUNE 9, 1908. G. M. LITTLE.

ELECTRODE FOR ARC LAMPS.

APPLICATION FILED MAY 10, 19061 INVENTOR WITNESSES ATTORNEY @H-a 6.15M

UNITED STATES PATENT OFFICE.

GEORGE M. LITTLE, 0F PITTSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSEELEC- TRIO & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRODE non nae-Limes.

Specification of Letters Patent.

Patented June 9, 1908.

Application filed lay 10,1908. Serial No. 816,181.

To all whom it may concern:

Be it known that I, GEORGE M. LITTLE, a citizen of the United States,and a resident of Pittsburg, in the county of Allegheny and State ofPennsylvania, have inventeda new and useful Improvement in Electrodesfor Arc-Lamps, of which the following is a specification.

My invention relates to are lamps and articularly to those in which oneof the e ectrodes is composed of materials which cause the arc to beluminous.

The object of my invention is to provide an anode for a lam of thecharacter indicated which will ena le ready starting of the lamp underall conditions as well as the production of a steady, uniform light.

' Arc lamps are now frequently provided with com osition electrodes ofsuch charac-' for that t 1e arcs produced are more luminous than thoseproduced between ordinary carbon electrodes and also such that they arever much less rapidly consumed. An electrode which has been foundsuitable in practice has been composed of a mixture of magnetic oxid ofiron which is a conductor both when hot and when cold and which givesconductivity to the electrode, oxid of titanium which lmpartsappropriate color and brilliancy to the arc, and oxid of chromium whichsteadies the arc and prevents the electrodes from being rapidlyconsumed, these substances being combined in various and suitableproportions. Other compositions of these metals or of others havingsimilar or suitable pro erties may also be emloyed. Such an 'e ectrodehas usually een employed as the cathode in combination with a cop erpositive electrode which is but very slow y consumed. In operation ofthe lam however, a slag forms on the anode that 1s composed of the oxidof copper, a very poor conductor when cold, which revents electricalcontact between the ecotrodes and consequently interferes with readystarting of the lamp after it has once been in use. For this reason ithas been proposed to employ iron for the positive electrode or someother metal, the oxid of which is a conductor. Iron, however, is morerapidly consumed than copper and what has been termed pooling frequentlyoccurs when it is employed; that is, the arc plays u on a comparativelysmall portion of the en of the composition electrode until the surfacebecomes hollowed and a depressed ool of the molten oxids forms, uponwhich t e are moves rapidly, resulting in flickering of the light.

I have, found that the advanta es pertainin to both copper and iron,wien employe as the positive electrodes in lamps of the characterindicated, may be secured and the disadvantages of 0th be obviated orreduced by providing a positive electrode that iscomposed of both ofthese metals in the roper relations and proportions. I

F1gure 1 of the accompanying drawing is an isometric view of theelectrodes of an arc lamp, one of which is constructed in accordancewith .my invention, and Figs. 2 and 3 are similar views ofmodifications. I

As here shown in Fig. 1, the anode 1 comprises a rod or cylinder of ironor other metal, the fused oxid of which is a conductor when cold,-havinlongitudinal radial slots or recesses'in which strips 2 of anothermetal, such as copper, are located. While I prefer that the main ortionof the anode be composed of iron and that the copper strips be placed inthe radial slots, a reversal of this arrangement -may be employed, ifdesired. Other metals than cop er and iron may also be employed withoute arting from the spirit of the invention so ong as the fused oxld ofone of the metals is a conductor when cold while the fused oxid of theother may or may not be a non-conductor when cold. For instance,

' silver may be conveniently employed instead of iron since the fusedoxid thereof is a conductor. The electrode may also be formed, ifdesired, as shown in Fig. 2 in which cylinders 3, 4, 5, 6 and 7 that arecomposed alternately of copper and iron placed one within another, or tmay be formed of plane strips or 'laminations 8 and 9 of copper andiron, as indicated in Fig. 3, or in any other suitable manner, it beinpreferable, however, in all cases, to ma e the outer layer or the largerportion of the superficial area that is not exposed to the arc of iron.With such an electrode, I have found that pooling does not occur andthat consequently a steady are results. The rate of consumption of theelectrode is also considerabl less than that of iron alone, and it hasbeen ound that, if the larger portion of the exposed area is composed 0iron, the life of the electrode may even be greater than that of copperalone, the iron serving as mechanical means for preventing-scaling ofthe oxid that forms upon the surfaces of the copper unexposed to theare, thereby preventing continued oxidation of the copper. A

I claim as my invention:

1. An are lamp electrode composed of copper and iron.

2. An arc lamp electrode com risin a rod of iron and strips of copperembe ded t erein.

3. An arc lamp electrode comprising a lurality of layers composedalternately of iron and copper.

' Anarc lamp electrode comprising a plurahty of layers composedalternately of a metal the fused oxid of which is a conductor and ametal the fused oxid of which is a nonconductor when cold. v

In testimony whereof, I have hereunto subscribed my name this lst day ofMay, 1906.

GEORGE M. LITTLE.

Witnesses:

., OTTO S. SOHAIRER,

BIRNEY HINES.

